Is /dev/ada2s1d there? Maybe it will mount as /home and you can adjust fstab
(Guessing).
If devices are plainly missing though, geom_mbr.ko and two others in /boot/loader.conf
may fix it (search that term in this or the freebsd forum...)

None of which is mountable. Removing module label however and setting the geom_kernel_debug sysctl allowed me to recreate the slice and partition. Unfortunately I was in a hurry and forgot to toggle the newfs switch. So....